JPS60178946A - Control device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To effectively control the factors of an engine, such as, for example, the injection amount of fuel, etc. by providing a pulse signal generating means and a heating pulse width determining means to a temperature sensing element having a temperature resistance characteristic and disposed in an intake-air passage. CONSTITUTION:A temperature sensing element 17 and an auxiliary temperature sensing element 30 are secured and set in the inside of an intake-air system 13. When the temperature of air rises upto a value above a specified differential temperature, an output signal from a differential amplifier 33 rises to reset a flip-flop circuit 34 which controls the base electrode of a transistor 36 in a pulse- like discontinuous manner. With this arrangement the amount of intake-air may be controlled with a high degreed of accuracy, thereby the control of the engine such as, for example, the control of fuel injection amount may be effectively carried out.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an intake air amount detection means used as one means for detecting the operating status of an internal combustion engine when the engine is electronically controlled. The present invention relates to a control device for an internal combustion engine that is improved so that a more accurate and effective air quantity signal is generated.

[Background of the Invention] When controlling an internal combustion engine electronically, it is necessary to constantly monitor the operating state of the engine, and engine rotational speed detecting means and engine temperature detecting means are used as means for monitoring the operating state. , exhaust gas concentration detection means, throttle opening detection means, etc., as well as intake air amount measurement and detection means. As a means for detecting the amount of intake air, for example, a thermal air flow rate sensor is used. It is configured to detect and measure the temperature change state of the thermal element.

In other words, a temperature sensing element having a temperature resistance characteristic is heated to a constant temperature by a heating current controlled in an analog manner, and the amount of heat radiated from the temperature sensing element in response to the air flow rate is determined by the resistance of the temperature sensing element. It is configured to detect and measure changes. Specifically, the air flow rate in the intake pipe is measured by a change in the value of the current flowing through the temperature sensing element.

However, in a structure in which the humidity sensing element is heated to a constant temperature using an analog-controlled current, the measured current value varies, for example, while the air flow rate changes by a factor of 100. It only changes by about twice,
Its measurement sensitivity is extremely low. Therefore, in order to use this air flow sensor for controlling an internal combustion engine, it is necessary to provide an offset processing means for the detection signal amplification circuit, and the control circuit for this tends to become complicated. .

In addition, when configuring an engine control device using a microcomputer, it is necessary to convert the analog output signal from the sensor υ into digital data and supply it to the control circuit. In this case, analog-to-digital conversion must be performed with sufficiently high precision. That is, a high-resolution A/D converter and a reference voltage power supply for this A/D converter are required to be extremely accurate.

Furthermore, in addition to the constant current type resistance wire type, there are also types with control means such as constant temperature type resistance wire type, constant potential difference type paper/drag type, etc., but these also have the same problems as above. We are prepared.

Furthermore, as a control means for such a temperature sensing element, a means for controlling the temperature sensing element to a constant temperature by means of a pulse heating control means has been considered as a means to solve the above-mentioned problem □. However, even if such a pulse heating control means is used, the output value can be increased to a certain extent, but precision in the pulse cycle for controlling the heating current and control precision in the heating voltage are also required. It is also subject to constraints from the operating environment. Furthermore, since pulse control is performed at a period unrelated to the internal combustion engine to be controlled, problems may arise in signal processing for engine control.

OBJECT OF THE INVENTION This invention has been made in view of the above points, and it is possible to measure the amount of intake air in a state that is most suitable for the operating conditions of the engine, and it is It is an object of the present invention to provide a control device for an internal combustion engine that enables air flow rate measurement with good sensitivity to be performed and effectively performs inter-li sub-controls such as fuel injection amount.

[Summary of the Invention] That is, in the control device for an internal combustion engine according to the present invention, a synchronization signal is generated based on a signal corresponding to the operating state, for example, a rotation signal, and a synchronization signal corresponding to the synchronization signal is generated. The heating current to the temperature sensing element of the thermal air flow rate detection device is set to tg+, and the setting range of this heating current is controlled in accordance with the temperature change state of the temperature sensing element. .

[Embodiments of the invention] ・ ・ Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an engine 110 control system that electronically controls the fuel injection amount, etc. in accordance with the operating state, and the intake air from the air filter 12 is not taken in through the intake pipe 13. The fuel is supplied to each cylinder of the engine 11 through a throttle valve 15 whose drive is controlled by an accelerator pedal 14. And the intake pipe 1
A temperature sensing element 17 constituting a thermal air amount detection device 1G is set inside the air conditioner 3. This II8 Onsakuko 1
1 is constituted by a heater made of, for example, platinum wire, which is heated under electric current control and has a temperature characteristic in which the resistance value changes depending on the temperature. The detection signal from this air flow rate detection unit 16 is configured by a microcomputer and is supplied to an engine control unit 18 that includes an engine control processing device. Warm element 1
7 is heated and controlled. The engine control unit 1-18 also receives a detection signal from a rotational speed detection device 19 that detects the rotational state of the engine 11, a cooling water temperature detection signal for the engine 11 (not shown in the figure), and an exhaust temperature. Detection signals, air-fuel ratio detection signals, etc. are supplied as operating state detection signals, and in response to these detection signals, the fuel injection amount most suitable for the operating state of the engine 11 at that time is calculated, and the engine 11 The unit injector 20 is set correspondingly to each cylinder.
a, 20b, . . . as a fuel injection time setting signal. In other words, the signal for setting the fuel injection amount in this case is a pulse-like signal with a duty set, and the data corresponding to the time width of this pulse-like signal is once set for each cylinder. It is stored in the registers 21a, 21b, . . . and stabilized, and the injector is controlled to open in that time range, and the injected fuel amount is set and controlled.

The rotational speed detection device 19 includes cams 191 and 192 that are rotationally driven coaxially with the engine 11, and a rotating plate 193 that detects the rotational angle and has a large number of teeth.
91. Electromagnetic pickups 194 to 196 are set to face each of the rotating plate 193 and the rotary plate 193, and signals corresponding to a specific rotation angle of the engine 11 and signals for counting and detecting the rotation angle position are transmitted from the pickups 194 to 196. It is configured to take out.

Fuel taken out from a fuel tank 23 by a fuel pump 22 is distributed and coupled via a distributor 24 to injectors 20a, 20b, . . . provided for each cylinder of the engine 11, respectively. Here, the pressure of the fuel supplied to the distributor 24 is controlled to be constant by a pressure regulator 25, and the amount of fuel injected is accurately determined by the valve opening time of the injector section calculated above. The settings are controlled.

The engine control unit 18 also gives commands to the igniter 26, and ignition coils 28a provided for each cylinder via the distributor 27.
28b, . . . , the ignition signal is distributed and supplied to the engine 11 to control the operation of the engine 11 in accordance with the operating condition detection signal.

FIG. 2 shows the temperature sensing element 17 used in the intake air amount detection device 16 used in the engine control system as described above, which has concentration characteristics with respect to the ceramic bobbin 171. A platinum resistance wire 172 is wound as a resistance wire. Both end portions of this bobbin 171 are provided with shirts l-173 made of a good conductor.
, 174 is provided protrudingly as a support shaft, and this shirt l-173
, 174, both ends of the resistance wire 172 are connected. The shafts 173 and 174 are supported and set by respective bins 175 and 176 made of a conductor, so that a heating current is supplied to the resistor #11172 via the bins 175 and 176. The resistance fFiA 172 portion of the temperature sensing element 17 configured as described above is set inside the intake pipe 13 so as to be exposed to the air flow passing through the intake pipe 13.

FIG. 3 shows another example of the configuration of the temperature-sensitive element 17, in which a resistance wire 172 that becomes a heating element having temperature characteristics is formed by printed wiring or the like on a film 177 made of an insulator. , this vA177 is connected to a support substrate 178 made of an insulator.
Make sure to set it to support. Then, a wiring 179a connected to the resistance wire 172 on the surface of this substrate 178.
, 179b are formed to control supply of heating current to the resistance wire 172.

FIG. 4 shows the circuit configuration of the air flow rate detection device 16 used as described above, in which the temperature sensing element 17 is fixedly set inside the intake pipe 13 as described above. , A sub-humidity sensing element 30 is fixedly set inside the intake pipe 13 .

The sub-temperature-sensing element 30 is composed of a resistance wire having temperature characteristics, such as a platinum wire, like the temperature-sensing element 17 described above, and its resistance varies depending on the temperature of the air passing through the inside of the intake pipe 13. A value is set and used as an air temperature measurement means.

A bridge circuit is constituted by both the humidity sensing elements 17 and 30 and the fixed resistors 31 and 32, and the connection points between the temperature sensing elements 17I3 and 30 and the resistors 31 and 32 are respectively , are connected to the input terminals of the differential amplifier 33 to detect temperature changes of the temperature sensing element 17.

That is, a heating current is supplied to the temperature sensing element 17,
When the humidity rises above a specified temperature difference with respect to the air temperature detected by the sub-temperature sensing element 30, the output signal from the differential amplifier 33 rises and the flip-flop circuit 34 is reset. Ru. In this case, the flip-flop circuit 34 is controlled by the rotation synchronization signal from the rotation speed detection device 19 synchronized with the rotation of the engine 11 to correspond to a specific rotation angle of the engine 11. .

The set output signal from the flip-flop circuit 34 is routed through the buffer 7 amplifier 35 so as not to be taken out as an output signal with a controlled pulse width.
1- The base electrode of the transistor 36 is controlled to control the power supply to the bridge circuit including the temperature sensing element 17, 30 in a pulsed manner. In this case, the reference power supply 37 and the differential amplifier 38 set the pulsed power supply voltage supplied to the bridge circuit in steps of I$.

That is, in the device configured as described above, if a synchronization signal is generated in the state shown in FIG. 5A in response to the rotation of the engine 11, the flip-flop The pull circuit 34 is set, and the output signal from this circuit 34 rises as shown in (B) of the figure. In response to the rise of the signal from the Noritsubu flop circuit 34, the transistor 36 is turned on, and a heating current is supplied to the B element 17.
The temperature of this temperature sensing element 17 begins to rise as shown in (C) of the figure.

In this way, when the temperature of the sensor) B element 17 rises and its resistance value gradually increases, and the terminal voltage becomes lower than the potential set by the sub-temperature sensor 30,
The output signal from the differential amplifier 33 rises as shown in <D> in the figure, and the flip-flop circuit 34 is reset.

That is, when the heating current to the temperature sensing element 17 is constant, the temperature of the temperature sensing cord 17 increases in a state corresponding to the air flow rate in the intake pipe 13, and therefore the temperature of the flip-flop circuit 34 increases. Reset from the time of setting! The time interval from . That is, the time interval during which the flip-flop circuit 34 is set is the state corresponding to the amount of intake air, and the pulse-like signal generated in response to the setting and resetting of the flip-flop circuit 34 is The decouple is a signal corresponding to the measured air amount, and this signal is supplied to the engine 1liilJi units 1 to 18 as an output signal of the air flow rate detection device 16, and is used for calculation control of the fuel injection amount. It is something that will be offered to people.

In the air flow rate detection device 16 configured as described above, since the temperature sensing element 17 is heated and controlled by the duty ratio, it is more sensitive to changes in the air flow rate than a device that continuously conducts current heating. It is possible to make large changes in the output signal. Furthermore, since this output signal is in the form of a pulse, it can be easily converted into digital data by simple means such as counting clock pulses, and is used to perform digital control. Applications to the control unit 18 can be executed in a very simple manner.

Further, even if such a pulse duty control means is used, in the device 16 shown in the above embodiment,
The reference time for determining the cycle is set in synchronization with the rotation of the engine 11, and therefore no special circuit is required for this purpose, which is sufficiently advantageous in terms of measurement accuracy, cost, etc. be able to. In this case, since the heating control of the temperature sensing element 17 is performed in synchronization with the rotation of the engine 11 and the corresponding output signal is extracted, it is most suitable for application to engine control. The state is such that the output characteristics can be obtained.

Here, due to the relationship between the rotation speed N of the engine 11 and the air flow rate,
The operating range of the engine 11 is as shown in FIG. In this figure, a indicates an idle state, b indicates an idle rotation full load state, C indicates a maximum rotation speed full load state, and d indicates a racing state at the maximum rotation speed. The inside of the rectangle a to d is the actual usage area A of the engine, and the outside areas B and C are completely meaningless in the normal usage area. Fig. 7 shows the relationship between the output pulse width of the air flow suspension detection device @16 and the actual air flow rate, and points a to d and areas A to C correspond to Fig. 6, respectively. . Since the above unnecessary regions IQ 3 and C exist both in the higher output and the lower output, it is possible to measure the air flow rate over a wide range without measuring critical values. It is something. Furthermore, even if this output signal is converted into digital data, the resolution will deteriorate only in extremely rare cases of high rotation and low load, as shown by d. being in an unclaimed state.

In addition, when obtaining such a pulsed output signal, the integral value of one period of the pulse period is output. Considering this point, it is possible to obtain the pulsed output signal in synchronization with the rotation of the engine. Since the intake pulsation is in a state where it is generated, the influence of intake pulsation is significantly reduced.

The synchronized state of this output signal is determined by the engine 1 in the above embodiment.
I explained that it should be set to synchronize with the rotation of 1, but
This may be controlled in synchronization with the operating state of the engine 11; for example, it may be controlled in synchronization with the fuel injection timing. When synchronized with fuel injection in this way, even if the injection interval varies, the average output over that injection period can be obtained, which is most suitable for engine operation control. This makes it possible to obtain an air flow rate measurement detection signal in the same state.

FIG. 8 shows another embodiment of the air flow rate detection device 1G, in which the output j signal from the differential amplifier 33 is supplied to a one-chip microcomputer 40. A synchronizing signal corresponding to the operation of the engine is inputted to the microcomputer 40 together with the output signal from the differential amplifier 33, and the microcomputer 40 receives a synchronization signal corresponding to the operation of the engine. It controls the constant voltage circuit.

In such a device, the signal input from the differential amplifier 33 to the microcomputer 40 is the signal shown in (D) in FIG. By measuring , it becomes possible to measure the time corresponding to the pulse width of the pulse signal as shown in FIG. 5(B), for example, by counting clock pulses. be. Therefore, the output signal from the microcomputer 40 is not a pulse width signal as shown in the above embodiment, but is a binary coded signal from the serial port, and is sent to the engine control unit 18. Bye. Alternatively, it may be calculated within the microcomputer 40, perform processing such as double lookup, and output as a signal converted into an air flow rate signal, basic fuel injection amount, etc.

Moreover, the temperature sensing element 17 used in the above embodiment is
Each of them is configured as a heating element having its own temperature characteristics. However, as shown in FIG. 9, for example, this temperature sensing element 17 is constructed by combining a heating element 17a which generates heat with a heating current and a resistance temperature sensing element 171 which has temperature characteristics. The elements 17b are arranged close to each other so as to be heated. That is, when the heating element 17a generates heat due to the pulsed heating current, this heat is directly transferred to the resistance element 17.
1), and the temperature state of this resistance element 17b is changed and set depending on the air flow rate. Therefore, by changing the resistance value of this resistance element 171), a signal corresponding to the air flow rate similar to that of the previous embodiment is outputted.

[Effects of the Invention] As described above, according to the present invention, the intake air flow rate can be measured and detected in a state that is most suitable for the operating state of an internal combustion engine such as an engine, and the detection sensitivity is also sufficiently good. It can be in various states. In particular, since the air flow rate measurement operation is performed in synchronization with the engine rotation and other operating conditions, it is highly effective in effectively performing electronic control of the engine such as fuel injection amount control. It is something that

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a control system explaining a control device for an internal combustion engine according to an embodiment of the present invention, and FIGS. 2 and 3 respectively show a temperature sensing element of an air flow rate detection device used in the above embodiment. 4 is a diagram illustrating the circuit configuration of the air flow rate detection device, FIG. 5 is a signal waveform diagram illustrating the operation of the detection device, and FIGS. 6 and 7 are respectively A diagram showing the relationship between the rotation speed and the output signal pulse width with respect to the flow rate, and FIGS. 8 and 9 are diagrams explaining other embodiments of the present invention, respectively. DESCRIPTION OF SYMBOLS 11... Engine, 13... Intake pipe, 15... Throttle valve, 16... Air flow rate detection device, 17...
Temperature sensing element, 18...Engine control unit, 19...
- Rotation speed detection device, 20a, 20b...Unit injector, 30...Sub-temperature sensing element, 33...Differential amplifier, 34...Flip-flop circuit, 36...Transistor, 40... microcomputer. Applicant's representative Patent attorney Takehiko Suzue Figure 4 Figure 6 Figure 7 Figure 8 Figure 9

Claims (2)

[Claims] (1) A temperature sensing element having a temperature resistance characteristic that is placed in the intake system of an internal combustion engine and whose heat generation is controlled by a heating current, and the temperature sensing element that rises in synchronization with a synchronous signal corresponding to the operating state of the engine. means for generating a pulse-like signal for setting a heating current to the element; and a means for detecting the humidity of the temperature-sensitive element, which is heated and controlled by the pulse-like heating current generated by the means, in relation to the air temperature; A control device for an internal combustion engine, comprising means for setting a heating pulse width of the pulsed signal in response to a rise in temperature of a temperature sensing element to a specific temperature. (2) The control device for an internal combustion engine according to claim 1, wherein the synchronous signal corresponding to the operating state is generated in response to the rotational operation of the internal combustion engine.